Conventionally, there has been disclosed an optical module or device for receiving light in JP 09-806458 (A). The optical device 200 has a substrate or positioning block 201 made of glass. A major surface 202 of the block 201 has a V-shaped groove 203 and an inclined, rectangular-shaped groove 204 crossing the V-shaped groove 203 both defined therein. The rectangular-shaped groove 204 receives an optical filter 205 for reflecting light having a wavelength of λ1 and transmitting another light having a wavelength of λ2. The V-shaped groove 203 receives first and second optical fibers 206 and 207 on opposite sides of the filter 205, respectively. The major surface 202 supports electrodes 208, which in turn support an optical element 209 with a light receiver through solder joints 210 for connecting between the light receiver 209 and the electrodes 208.
In operation, light having wavelengths of λ1 and λ2 is advanced from an open end of the first optical fiber 206 to the filter 205 where light λ1 is reflected toward the light receiver 209 and light λ2 is transmitted therethrough into the second optical fiber 207.
The optical device, however, has several drawbacks. For example, as can be seen from the drawing, the light receiver 209 is supported on the electrodes 208 and also solder joints 210 mounted on the electrodes 211, so that it is significantly spaced away from the filter 205, causing an expansion of light travelling from a reflecting portion of the filter 205 to the light receiver 209. This means that a small light detector fails to receive the whole light reflected by the filter, which prevents a compact and high-responsive light receiver suitable for a high-speed communication from being incorporated in such optical device.
Also, according to the publication, the angled groove for receiving the filter is formed after the optical fiber has been bonded on the block, which disadvantageously enlarges a distance between the opposing end surfaces of the separated optical fibers. This deteriorates an efficiency of light transmission between the opposing optical fibers.
Further, the filter is not secured in the groove, which may cause the filter to bend or curve. This changes a direction of light reflected by the filter, reducing an efficiency for receiving light by the light receiver.